package com.wang.netStudy.chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable {
    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;

        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while (true) {
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));

                socket.send(packet);

                if (data.equals("bye")) {
                    break;
                }
            }catch (Exception e){
                e.printStackTrace();
            }
        }

        socket.close();
    }
}

package com.wang.netStudy.chat;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class TalkReceive implements Runnable{
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;

    public TalkReceive(int port, String msgFrom) {
        this.port = port;
        this.msgFrom = msgFrom;

        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        while (true){
            try {
                //准备接收包裹
                byte[] container = new byte[1024];

                DatagramPacket packet = new DatagramPacket(container,0,container.length);

                socket.receive(packet);//阻塞式接收包裹

                //断开连接，bye
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);

                System.out.println(msgFrom + "：" + receiveData);

                if (receiveData.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        socket.close();
    }
}

package com.wang.netStudy.chat;

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777, "loaclhost", 9999)).start();
        new Thread(new TalkReceive(8888, "老师")).start();
    }
}

package com.wang.netStudy.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        new Thread(new TalkSend(5555, "localhost", 8888)).start();
        new Thread(new TalkReceive(9999, "学生")).start();
    }
}